Involuting drawing instrument.



0. E. McGASKILL.

INVOLUTING DRAWING INSTRUMENT.

APPLICATION FILED NOV. 17I 1913.

1N VEN TOR.

a; MFCASIULL,

BY mm WITNESSES:

TTO E Y.

OSCAR E. MOCASKILL, 0F FUR/1 NORTH, TEXAS.

INVOLUTING DRA'WING IN STRUMEN'I.

Specification of Letters Patent.

Patented Aug. 11, 1914.

Application filed November 17, 1913. Serial No. 801,358.

To all whom it may concern Be it known that I, OSCAR E. MoCAsKILL, a citizen of the United States, residing at Fort Worth, in the county of Tarrant and State of Texas, have invented certain new and useful Improvements in Involuting Drawing Instruments, of which the follow ing is a specification.

This invention relates to a drawing instrument and particularly to a drawing instrument for drawing involuting curves, and the object is to provide a simple and highly efficient mechanism for using a drawing pen or pencil, or other instrument, and which will be easily operated.

Other objects and advantages will be fully explained in the following description and the invention will be more particularly pointed out in the claims.

Reference is had to the accompanying drawings which form a part of this application.

Figure l is a side elevation of the drawing instrument. Fig. 2 is a side elevation of the spacing and adjustment wheel and guide. Fig. 8 is an end view of the pen carrier or chuck. Fig. 3 is a vertical section of the same. Fig. 3 is a bottom plan view of the Fig. 4 is a horizontal section of the same. pivot post taken along the line JJ of Fig. 1. Fig. 5 is a detail view of the adjusting screw shaft. Fig. 6 is a side elevation, showing a variation in the pen carrier. Fig. 7 an end elevation of the same.

Similar characters of reference are used to indicate the same parts throughout the several views.

The drawing instrument includes a wheel A which is pro-vided with a rubber rim or with a rim of some substance which will have some friction. This wheel is for the purpose of spacing the distance between the curves to be made and also for adjusting a screw shaft C. The wheel A may be considered also a tangential guide. rigid with the shaft C by a set screw B. The screw shaft C is journaled in a pivot post D and turns freely in this post. The screw shaft C has an annular groove K therein and a set screw I is screwed into the pivot post D and projects into the groove K to prevent longitudinal movement of the shaft G through the pivot post D. A guide rod E is fixedly mounted in the pivot post D and held therein by a pin L. The carrier F for the drawing instrument has apertures M for The wheel A is made the guide E and N for the screw shaft C. The carrier F will move freely on the guide rod E.

When the instrument is in operation the wheel A is moved around on the paper or cloth or other material on which the drawing is being made and as the wheel A moves it turns the shaft 0 and as the shaft 0 turns the carrier F will be moved in the direction of the threads on the shaft C. It will be noted that the threads on the shaft C may be either right or left threads.

A pen H is provided and enters a socket F in the lower part of the carrier F. The pen H is held in place by a spring G which has one end rigid in the carrier F and the other end projecting into the upper part of the pen H. This provision allows a yielding motion to the pen and will always insure contact of the pen on the paper or cloth or other material on which the curves are to be drawn. The pen H is provided with a set screw 0 for opening orclosing the two parts of the pen for the purpose of drawing narrower or wider lines.

A variation of the pen holder or carrier is shown in Figs. 6 and 7. The pen H is provided with a shank P and a socket V is formed on one edge of the carrier F. The shank P will move freely through the socket V and is connected to a holder T above the carrier F. The shank P is made rigid with the bar T and a spiral spring R is mounted on the shank P between the carrier F and the pen H. The shank P can thus move freely through the socket V, but is held yieldingly downward by a spiral spring R. The bar T is guided in its vertical movement by a pin S which is rigid with the carrier F. The pin S serves as one guide and the socket V serves as another guide for the vertical movement of the pen H.

The function of the rod E is to prevent the turning of the carrier F during a Writing or drawing operation and also, as above described, to guide the pen H and to prevent wabbling motion of the same in its radial movement.

It will be observed that by reason of a right thread on the shaft O the pen H may be set near the pivot post D to commence a'curve, and as the instrument is operated by turning the wheel A about the pivot post D the curve will become uniformly larger as the wheel A is turned because the thread on the shaft O is uniform and each tinually space the pen H from the pivot,

post D to cause a larger curve. It will be noted that the wheel A is adjustable on the shaft C and may be set at any point inclicated, by the numerals 2 to 10, inclusive. When the wheel A is set close to the pivot post D, the curved line being made will run close to theprevious curve, but when the wheel is set farther from the post D, the space between the curves will become wider. The farther the Wheel is away fron the pivot post D, the in'oi e times the shaft C will turn on one rotation about the pivot point and thus move the chuck or carriei F the faster away from the pivot point.

What I claim, is p H e H A dra-Wing instrument comprising a pivot post a screw shaft journaled in said post, means for preventing longitudinal inovernentof said shaft through said post, a guide and spacing wheel rigid withsaid Shaina carrier inountedon said shaft and provided .With a threaded I Opening therethrough for said shaft, saidshaft having threads engagingthe threads insaid carrier a guide rigid with saidpost and ext eme throilgh said carrier, and a pen carried by ,A. i 7 sa d earner, H I 2, A drawin nstrument havlng a pivot 1965b, ,i ll t i urnal edin said post and liavr mg Screw threads on ,end, a wheel rigid with the other end of sa d shaft for turning said shaf t, a carrier mounted onthe threaded portion of said shaft and carrying a pen saidpivot post and projecting through said,

opening, and a drawing pen yieldingly mounted on the saidcarrier, t i

4. A drawing instrument havinga pivot post provided witha bearing, ,a screw shaft journaled in said bearing and provided with threads on one end, an adjusting wheel rigid withthe other endof lsaid shafha car,- rier carried on the threaded portion of said shaft and havingan, aperture throughthe upper part thereof, a guide moving freely through said aperturev and rigid with said pivot post, a pen rnounted in said carrier, and means provided for ayieldiiig vertical motion of said pen 1; ,p h t In testimony whereof,;l set-my hand in the presence of two witnesses, this 16th day of October, 1913. g OSCARE. MCCASKILE:

wa t n e 1 A. L. JAoK'soN,

J W. Smr'r.

2; 2:; J e. 15 r w -11 F M :1; 1, -t' 1 big Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Tatents, Washington, D. G. 

